The BBC says police made many arrests and used tear gas to disperse protesters who had set fires to tires and trash bins in Tehran.

Witnesses tell the BBC Persian service that scores of people gathered outside Iran's central bank to call for its governor to resign and to chant anti-government slogans.

The BBC quotes financial experts as saying the rial -- which has lost a third of its value against the dollar in one week -- has been hard hit by Western financial sanctions imposed over Iran's nuclear program.

An oil embargo has put the squeeze on foreign currency earnings and nervous Iranians are rushing to swap their rials for hard currency dollars, the BBC says.

Tehran's main bazaar, one of the city's major shopping areas, was closed today, according to witnesses. One shopkeeper who sells household goods there tells Reuters that the instability of the rial is making it hard for merchants to quote accurate prices.